The present invention generally relates to a rotary head of a magnetic recording and reproducing apparatus, and more particularly, to a magnetic recording and reproducing apparatus for effecting recording and reproducing with a magnetic head which is movable in the width direction of a magnetic tape.
In recent years, a method of correctly tracing on the recording track by a magnetic head so as to obtain noiseless reproduced pictures has been proposed and carried out by controlling the magnetic head using a magnetic head driving apparatus mounted on a rotary cylinder during the special reproducing time of slow motion reproduction, fast forward reproduction and so on in the magnetic recording and reproducing apparatus. It is necessary to correctly detect the position of the magnetic head so as to effect a recording operation usingthe magnetic head.
A magnetic head driving apparatus (FIG. 5) used conventionally in a rotary head of a magnetic recording and reproducing apparatus is shown. FIG. 5 is a sectional view of the conventional magnetic head driving apparatus shown, for example in Japanese Laid-Open Patent Application Tokukaisho No. 63-173217. In FIG. 5, reference numeral 1 denotes a magnetic head, and reference numeral 2 denotes a coil portion. The coil portion 2 is composed of a cylindrically shaped coil bobbin 2a and a coil 2b wound around it. A hollow cylindrically shaped outer peripheral second yoke 5 has a larger inside diameter than the coil bobbin 2a, and is made of a material which has a high permeability. Both an outer peripheral first yoke 6a, and an outer peripheral third yoke 6b are made of material which has a high permeability and are secured to both the ends of the cylindrically shaped outer peripheral second yoke 5. The outside diameter portion of a first gimbal spring 3a having a spring extending portion 10 with a magnetic head 1 being mounted on it is mounted on the first yoke 6a or the second yoke 5. The outside diameter of a second gimbal spring 3b is mounted on the second yoke 5 or the third yoke 6b. The inner edge portion of a first gimbal spring 3a is secured on the coil bobbin 2a by a first mounting member 4a. The inner edge portion of a second gimbal spring 3b is secured on the coil bobbin 2a by a second mounting member 4b. A cylindrically shaped first permanent magnet 7a and a cylindrically shaped second permanent magnet 7b are arranged adjacent to both the ends of the cylindrically shaped magnetic core 8, and are arranged coaxially within the cylindrically shaped second yoke 5.
When an electric current flows through the coil 2b, an electromagnetic force in the axial direction is caused in the coil 2b by Fieming's left-hand rule. The coil bobbin 2a moves in the axial direction, because the upper and lower end portions are respectively supported by the first gimbal spring 3a and the second gimbal spring 3b. The magnetic head 1 is also moved in the axial direction through the first gimbal spring 3a secured onto the coil bobbin 2a.
In such a conventional magnetic recording and reproducing apparatus as described hereinabove, there is a problem in that a flapping angle, an azimuth angle of the magnetic head 1 cannot be ensured, and the recording operation cannot be correctly effected in accordance with the format, because the positional accuracy of the magnetic head 1 depends upon the assembling accuracy of the magnetic head driving apparatus and the magnetic head 1 cannot be correctly positioned as the magnetic head 1 is mounted upon the extending portion 10 of the first gimbal spring 3a.
There is a problem in that the leakage flux of the magnetic circuit can apply ill influences upon the magnetic head 1, because the magnetic head 1 is disposed in extreme proximity to the magnetic circuit.
The position of the magnetic head 1 is difficult to correctly detect in the recording operation using the magnetic head 1 of the magnetic head driving apparatus, with a problem in that the recording operation cannot be effected correctly in accordance with the format.